You could also use locate to look for commands. Why do people use locate if find does the job? Because locate is much faster than find since it just searches through database(s) of indexed locations to find your file/regex.

Examples:

locate some-file.avi searches through database(s) of almost every file on the disk for a file called "some-file.avi".

locate -i "some-file.avi" will ignore the case of the file you are searching for.

locate -i "*.txt" will display a list of locations of all the files with **.txt* extension on your system.

man locate for more info on the file.

You might need to run updatedb first to ensure the index database is up to date, otherwise, 'locate' might not return what you are looking for.

You should try then the KDE search. It is far better than the gnome one. I am still waiting for Nautilus to catch up with the versatility that the KDE search system has. Dolphin/Konqueror are far better because of it.
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Luis Alvarado♦Dec 21 '11 at 4:53

Yeah, I was thinking about switching to Kubuntu actually. I'll take a look at it.
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djangofanDec 22 '11 at 1:04

If you're looking for a string inside a file, you can use grep. Here's a sample command:

grep -r -i "some string" /home/yourusername

This will find "some string" in /home/yourusername directory. The search will ignore case (-i) and recurse directories (-r). You can use / as the directory to search in the whole directory but that might not be very efficient.